Studies of human lens proteins relative to changes induced by aging and exposure to environmental UV-light will continue. They will include analytical work to identify or characterize a low molecular weight protein and a fluorescent chromophore that is loosely attached to it. This is a light sensitive unit, that is altered by UV-light and changes in content with aging. The association of low molecular weight proteins with fiber membranes is also being investigated. Inactivation of ocular tissue enzymes by a tryptophan photoproduct plus exposure to near-UV light will be studied on a mechanistic level. The importance of this loss of enzymatic activity to the functioning of ocular tissues is under investigation. Further studies of UV light damage to the retinas stimulated by the removal of the lens of the eye are in progress using guinea pigs as test animals.